This news release is available in German.
The European Research Council (ERC) has granted EUR 1.7 million funding to the research project "Vertebrate Herbivory" led by Dr. Thomas Tütken at Johannes Gutenberg University Mainz. This project aims to investigate when the first land-based vertebrates began to use plants as a new food source. Tütken joined the Applied and Analytical Paleontology work group at Mainz University in October 2013. His particular specialization is the isotope analysis of fossilized bones and teeth. The ERC is providing a Consolidator Grant to fund his research, which focuses on the diet of the first terrestrial vertebrates, over the next five years. Tütken will analyze fossil teeth from mammal predecessors and dinosaurs to determine whether these extinct animals ate plants, insects, or other vertebrates. This information will allow for the reconstruction of past food webs of early land vertebrates and the extinction patterns of individual species in order to better understand the evolution of reptiles, birds, and mammals as a whole.
Food is a major factor in the evolution of vertebrates. The first vertebrates that emerged from water onto the land about 380 million years ago likely ate insects. The assumption being that insects were easier to find and to digest for vertebrates compared to plants with their high content of cellulose. "The first herbivores appeared at the transition from the Carboniferous to the Permian period about 300 million years ago. However, herbivores evolved multiple times from faunivores at later periods, which proves that this process was not a unique event," explained Tütken. The first herbivores were probably mammal-like reptiles known as synapsids from which the mammals developed. Later, about 210 million years ago, some of the dinosaurs also evolved into purely herbivorous species.
Fossil teeth record dietary signals
Only fossil remains can tell us what exactly the diet of extinct vertebrates was. "An important indicator is the shape of their teeth, i.e., whether they were suited for grinding or slicing food. However, we will look more closely at what was actually eaten by analyzing the chemical and mechanical traces that the ingested food leaves in and on the teeth," added Tütken. For this purpose, the paleontologist will be measuring the calcium isotopes in tooth enamel and looking for traces of wear on tooth surfaces. For instance, a low calcium isotope ratio in tooth enamel indicates the consumption of bone and that the animal was thus a carnivore. In contrast, herbivores have higher calcium isotope ratios in their enamel and insectivores have even higher ratios. Moreover, the three-dimensional relief of the tooth surface on the nanometer scale reflects the abrasion caused by the animal's last meals. In a new research concept, the two techniques will be combined for the first time on the same teeth. The approach will be developed and tested by controlled feeding experiments of reptiles and mammals with animal and plant fodder.
In the next step, the methods will be used to investigate fossil teeth from various fossil sites around the world, including those from the famous Permian deposits of the Karoo Basin in South Africa that yielded skeletal remains of Lystrosaurus and other presumably herbivorous, mammal-like reptiles. Several years ago, the fossil remains of an edaphosaur were found in the Late Carboniferous Remigiusberg Formation near Kusel in Rhineland-Palatinate in Germany. This synapsid was probably an early herbivore and its teeth will also be analyzed.
An ERC Consolidator Grant is one of the most valuable EU funding awards given to researchers. The European Research Council uses these grants to support excellent researchers at the start of their independent careers, specifically 7 to 12 years following their PhD when they are developing their own research program. In order to be awarded a grant, applicants must not only demonstrate excellence in research but also provide evidence for the groundbreaking approach of their project and its feasibility.